Short circuiter



July 15 1924,

1,501,284,` E. P. LARSH SHORT CIRCUITER Filed Jan. l0, 1922 ATTORNEY.

y a citizen of the United States,

Patented duly. l5,

' UNITED STATES PATENT ori-fica l i ornanomonxo. l i l snoa'r omcurrn.

puede mea nanny 10,1512. vsemi 10.523,2.

Toallwliomtmay cwwem: Be it known that'I, Evnnm'r P. Laken, residing at Dayton, in the county of Montgomery and State of Ohio, have invented certain new and usefulV Im 'rovements in Short Circuiters, of whic the followingy is a specication. v

This invention relates tovelectric motors t and more particularly to a short circuiting or operation chan device for alternating current motors oute repulsion induction t pe, by which the motor is automatically c ange froma repulsion starting condition `to an induction runnin condition and viceversa in accordancewit v-ariations of speed. The object ofthe invention isto simplify the structure as well as the means yand mode of operation of such circuit changin ldevices whereby they'will not only be c eag- -ened inconstruction, but will be more e automatlc 1n operat1on,.un1V

cient in use, form in action, automatically controlled, and unlikely to get out ,of repair.

A further object' of the invention is to provide improved means operated by centrifugal tendency by which the commutator bars are automatically connected with a common electrical conductor, which will promptly VArespond to -variations of speed above and be ow a predetermined rate of rotation.

A further .object of the invention is to provide a short circuitingor current changling device, which will have a wiping actionv insuring perfect electrical contact, in which' this wipin action will befurther effected under yiel ing pressure thereby .obviating any chatter or vibration and the incident arcin and-burning of the contact surfaces.

Aurther object of the invention is to provide means. for controlling the A'movement of the .short circuiting or current chan ing members whereby their movement to egect the alternation of the motor from .repulsion to induction operation and vice versa will be effected by a quick movement in either ,direction i A further object of the invention is to provide such a short circuiting or current l changing device which will be compact, of

few parts, and having no pivot joints,'nor

indirect movement, but in which the current controlling devices are directly operated b centrifugal tendency.

Wit the above primary and other incidental objects in view asA will more fully appear in the specification, the invention .Y

consists of the features of construction, the parts and, combinations thereof, and the mode of operation or their equivalents, as

hereinafter described and set forth in the applied 4.- is a perspective view of' the short circuiter oil' the shaft. Fig. 5 is a detail sectional View Vof a modification of the construction shown in the preceding figures, wherein the cont-act member moves Idiagonally to effect the wiping or sliding contact. Fig. 6 is a similarldetailA view of substantially the `same construction as shown in Fig. 5, but emplo g double ide elements. Fig. `7 is a etail sectiona view of a further modiiication, wherein the contact member is yieldingly mounted for oscillatory movement into and out of engagement of the commutator bars. Fig. 8-is a similar detail sectional view of a. further modification, employing an intermediate contact, ac-

tuated by the movement ofthe centrifugally operated slugs or weights. Fi 9-is a modiiication-somewhat similar to Fig. 7, and Fig. i

10 is a' detail view of the driving vanes.

Like parts are indicated by similar characters of reference throughout the several views.

The structure of the electric motor per se, forms nc part of the Vpresent invention, which pertains Wholly to the short circuiting means for the commutator bars, by

which the motor is caused to operate-alternately as a repulsion motor and an induction motor.

An alternating current, repulsion-induction motor of the single phase 'type to which the present invention is particularly adapted is one which as the name indicates, Starts' -as a repulsion motor and as the speed approaches its normal or maximum rate of rotation automatically changes its character, and runs as an induction motor. Briefly described it consists of a field or stator of laminated toothed construction having a single winding supply lcircuit armature or rotor with a commutator engagedl by brushes during thestarting or repulsion period together with speed controlled devices for short circuiting the armature windings thru the commutator after the armature has attained a predetermined speed, which speed controlled means in some instances lifts the brushes from the commu- 'tator simultaneously with the short circuiting operation. There is no electrical connection between the stator and the rotor. The currents in the stator create an alternating flux which reacts on the rotor and induces its rotation. This type of motor, therefore, startsI as a simple repulsion motor without compensating or auxiliary windings and operates as a repulsion motor until the rotor or armature approaches a synchronous speed whereupon the speed controlled devices operate to automatically short circuit the armature winding thru the commutator. Thus the motor is automatically transformed from a repulsion type into an induction motor having what is essentially a squirrel cage rotor. lt is the improvement of the speedy operated governing or short circuiting device which forms the subject matter of the present invention. One of the advantages of a machine of this type is that it is inherently a constant speed motor having a high starting torque with low current consumption or minimumcurrent surge.

The typical repulsion motor without compensation gives the most efficient starting torque possible while the single phase 1nper se forms no pai-t of this invention, it has duction rotor with the squirrel cage armature or its equivalent adords, the most efficient motor when running.

A repulsion-induction type of motor combines these most desirable qualities in a single machine. As it possesses such high starting torque characteristics it is well adapted for .operating machinery which starts under full load, as pumps, air compressors, and grinding mills. Requiring no starter the are adapted for automatic control, or istance operation. They start quickly and operate quietly and smoothly. The above is offered merely to facilitate a thorough understanding of the purpose of the invention, and with no intent nor desire that it shall in any way be 'construed as .limiting or restricting the application or scope of the invention. Inasmuch as the construction of the motor not been illustrated. It is to be uderstood, however, that the short circuiting means forming the subject matter hereof is applicable to various styles of motors of the character heretofore indicated. Referring to the drawings, 1 is the armature shaft, on which is vcarriedthe usual commutatorcom- 9 and engaging in prising the core 25 about the periphery of which are loca-ted a continuous succession of commutator bars 3, insulated from the core 2l and from each other by intervening bodies of insulating material 4. The coin-V mutator bars 3 project somewhat beyond the terminal face of the core 2, and are v beveled or inclined on their inner faces as at 5, thereby affording a beveled peripheral flange upon the lateral face of the commutator. i

The short circuiting means is embodied in a unitar structure capable of bein assembled in ependent of the motor an applied thereto'or removed therefrom without the necessity of disassembling eitherthe motor or the short'circuiting means. However, this short circuiting. device may if desired be assembled directly upon the motor shaft.

The short circuiting device comprises a disc or support 6, adapted tovbe secured upon the armature shaft 1 adjacent to the face of the commutator, but in spaced relation therewith. In the present instance the disc 6 has been shown secured by by which the disc is securely pressed and clamped against a shoulder formed upon the armature shaft. Any other suitable means of mounting the disc may be employed. Thefixed in its relative position, in but it may be disc is thus relation with the commutator,

may be flexed to and from the lateral face of the commutator to vary the spaced relation; or the disc may be of rigid, inflexible construction, or material. Mounted about the vperiphery of the disc 6 is an annular series of radially disposed bifurcated slugs or centrifugally controlled contact elements 9. These contact elements or slugs'are some1 what wedge shaped or tapered, and are assembled side by each to form a continuous succession or band about the disc. The periphery of the disc extends within the bifurcation or slot 8 of the slugs 9, whereby the succession of slugs or centrifugally controlled weights, ride astride of the peripheral edge of the disc 6. `This slot or bifui-cation 8 of 'the slug is somewhat wider than the thickness of the disc 6, thereby allowing -the slugs or contactelements'a limited range of lateral or'shifting movement upon the disc. In addition to their inner biments are notched on their outer edges or faces as at l0. Extending about the assembled'series of contact slugs or` elements the external notches or bifurcations 10 thereof, is an'endless elasticl band 12. This able or desired material or character, but for convenience of manufacture and assembly a helical wire 'spring having its ends interconnected to form an endless band of suitable band 12I may be of any suit-.

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diameter has been shown. In lieu of this type of elastic band, acoiled wire'sprin t e convolutions of which 'extend entire y around the bl of plugs or contact elements may be emp oyed,"v or several convolutions of a flat spiral springlmay be utilized.

The elastic band 12 of w atever character it\i`nay be tends to contract the plugs or contact elements 9 into their innermost positions. `The disc 6 with its assembly of slugs or contact members, 'arranged astride the peripheral edge thereof, and retained in assembled. osition by the encirclin elastic band 12 orms the short circuit unit, which vmay be made up independent of the motor structure, and applied thereto or may be asiir sembled directly u n the motor shaft as is found most convenient or desirable. It is located in juxtaposition to the lateral face of the commutator core 2, with theinclined. or beveled ends Yof thebars overhangi-ig the slugs or contact element 9 at the inner sidef the unit;

JTo protect the assembly of slugs or contact e ements from-injury and from the accumulation of dirt, dust, grease or otherV foreign material, which/might interfere with their fect contact with lthe commutator bars, vere ma be provided adjacent thereto, a concavev sc 13, also carried u n the armature shaft 1 and the periphery o which overhan'gs the circular series of sl or conrtact elements. This concave diseis lixedly mounted u n the .armature shaft in its rela.- tion with commutator. In addition to its function of housing and protecting the aembly of contact elements` or slugs 9, this disc 13 may become a common contact or conductor with which the slugs or contact elements engage -t e while engaged With the beveled ends o commutator bars to alford a wedging action.

In other words, this cover or -housing mayA A become an abutment, against which the slu or contact members engage at one time whi e engagin beveled ends 5 of the commutator bars at t eother side. The slu are w or driven into this relation by t e centrifugal tendency as the unit -is rotated. However,

this disc orvhousing 13 is not essential andfth'e device will operate successfully if the the elastic contracting housiti or 'abutment disc 13 is wholly omit.

Centrifu l tendency induced by the rotation of tg: shaft 1, and the series of contact slugs 9, carried thereby, tends to move such slu outwardly, a -inst the tension of the centrifugal tendency is suicient to overcome the tension of the band 12, the slugs 9 in their outward ,movement will engage the beveled faces 5 ofthe overhanging ends of the commutator bar4, and lpon increased centrifugal influence will ten e short circuiting units and the to slide outwardly upon such-inclined faces. If the con` cave disc or housing 13 is'employed, this movement may continue until the slugs or contacts en age the inner face of the concave disc or shel 13. It is tobe noted that the shell or disc 'lov A131is also provided with a v beveled .face 15. This bevel of the1 shelloi disc 13 is, however, located somewhat more remotely from the center of rotation than the bevel 5 of the commutator bars.4 Thus the slugs will rst engage the bevel 5 of the commutator bars, and will then slide orars vand sliding dia onally these inclined surfaces in -a` serd within 'the heheal' band v12 to 'limit the outward movement of /the slugs. The tension of -the slu 's or contact members 5 upon the ends of t e commutator bars may be somewhat increased by makin the supportin -disc 6 of flexible' vor yiel ing mate-r rial, w ereby the pressure of the slugsupon the inclined faces 5 w'gill tend topres's lthe disc laterally,causing lit to assume a somewhat concave form as shown in Fig. 3, and

ico

'thereby utilizing the elasticity o r resiliency -of the disc to vincrease thecontact ressure.

of the slugs uponthe commutator ar.' kIf on the other hand the disc or sup ort 6 is of comparatively rigid material, t e slugs 'arep'ermitted am le side play or freedom of movement by t e relation dimensions of the slot or bifurcations 10 and the thickness of the disc to effect a yielding lateral movement.' The tendencyof the slugs of course is to move directly outward in a plane perpendicul'ar to the axis of'rotation.

The engagement of the slugs with .the

beveled ends 5' of they commutator bar tends vto force the slugs laterally out of this plane of normal movement` and hence the slugs exert a wipin action under ressure uponl the faces of t e commutatorar. sures a action ov the slugs or contact vmembers u n the 'bars keeps such surfaces clean and bright and prevents the accumulation of dust, grease or foreign material, which might otherwise insulate such contacts.

In Fig. 5 there is shown a modification wherein the bifurcated slutg; .are .mounted upon a concave disc 16, edly mounted This inrfect clean contact. The wipingl lis leo

upon the shaft 1', with its concave side toward the commutator and hence its periph- I ery isinclined in such direction. In this instance the commutator bars do not overhang nor possess the inclined ends 5, but terminatey in a plane perpendicular to the axis of rotation. The contactslugs v9 are quite similar to those previously described, beingbifurcated' at 10 to ride astride the periphery of the concave disc and notchedl at 8 `to receive .the elastic retaining band 12. The elastic band 12 is made 'up of a helical spring, the ends of which are Joined together, may enclose a limiting ring 14- as before described, which will limit vthe outward throw of the contact slugs. While the normal tendency of these slulgsor contact elements will be to move ra ially in a plane perpendicular'to the axis of rotation, the inclination of the supporting disc w1ll guidethe slugs or contact elements inwardly toward the commutator bars -in a diagonal path of travel. Tlseslugs at their limit of movement will engage the ends ofthe commutator bars with a w1p1ng or shdmg en-l f gagement, which will insure a perfect clean contact. The greater the speed, the greater will be the pressure of the contact members upon the commutator bars, and this engagement will infact limit their outward throw,`independent of auf)7 retaining ring` 14 or any other limiting means. 'As in the first instance, the disc 16, may be lflexible or yielding, whereby the elasticity orresiliencyof such disc may-'be utilized as a spring pressure fbr` the contact4 element? However such elasticity or yieldingfunc tion of the ldisc is not essential and such concave disc 16 may be of substantiall rigid construction. This construction di fers from the primary construction in vguiding the slugs or contact elements diagonally on to a fiat surface, I.with which they make sliding contact, whereas in the primary constructlon the slu s were permitted to move in straight radia lpaths into contact with a diagonal surface.

lIn normal position when the rotor is at rest, .or beforeit has attained its predeter:

mined o erating speed, the contact slugs 9 will-be lield in contracted position, upon the periphery of the disc by the band 12. However, as the rotorapproaches the predetermined speed at which the operation changes 4from repulsion to induction mode of operation, the Vslugswill move outwardly against the tension of the elastic band'12 until they v'contact the commutator bars, whether such'bars be ofthe overhanging .tapered or inclined type shown in Fig. 1,

or the lat faces to which the slugs move in a.- diagonal .direction as shown 1n Fig. 5. Further increase in speed induces greater centrifugal influence, and the bevel face 5 of the commutatorbars in the construction shown in Fi 5 or the dia onal movement of the slugs 1n Fig. 5 will ave a camming action by lwhich the slugs in their outward i* movement are deflected, thus affording av wiping and t e commutator bar. This wiping'or rubbing action, induced by the `diagonal or camming movement of either construction,

insures a .bright 'clean contact surface and perfect electrical engagement..

While the assembly of contactv slugs 9 upon .the supporting-disc of either type will normally rotate 1n unison therewith independor rubbing vcontact between the slugs ent ofany driving engagement and morej over, any independent rotation or slippage tervalsI and protruding between the'succes-Wo sive slugs of the series, dividing the contact slugs into a plurality of groups and affording a positive drivlng connection between ghe assembly of slugs and the carrier there# ride astride the peri he of the su ortin disc 16, the slugs arepintlelrposed betvpvlden twd parallel concentric spaced concave discs 18--18. They are retained in their inner.- most position by the elastic band 12 and operate diagonally to engage the ends of the commutator bars exactly as before described. The guide disc 18 is mounted in spaced fixed rate succeeding relatlon upon the armature shaft, and the assembly of slugs located therebetween.v

` In Fig.' 7 there is shown a further modification, wherein fthe bifurcated slugs ride upon the periphery of a disc, which may be either yielding or rigid, but the elastic retaining b'and is oli'set out of the plane of the points of engagement of the slugs effect an oscillatory or leverage movementoutwardly against'the tension of such band, and inwardly under its influence.

"In this construction, the supporting disc 2O is of o'setflanged construction, although a simple flat disc suc-h as shown in Fig. 1 might be employed with a second disc to form a rest or sto for the slugs. The slugs are notched or bifurcated at 21 toeA age over the periphery of the supporting isc,

while they are also notched or .recessed on the .opposite edge at 22 to receive the elastic band 12. There is preferably pro" 23 of convided a retaining disc or housing p e supportcave form, which overhangs t ing or fulcrum ends of the slugs to retain ln Fig: 6 there is shown a construction i 4 guite similar to that of Fig. 5, except that 1n lieu Aof slotting or bifurcating the slugs to flexible overhanging fingers or tongues 26,

Wardly and backwardly to afford bearing centrifugally controlled slugs 9 are enclosedengagement with the metal faces of the comthe .invention has beeny described in lanouage more or less specific as to structural nerends of the slugs tend -to move outward, eatures, it'is to be understood that the inthe slugs'fulcruming upon the edge of the vention is not limited to the s ilic details supporting disc,.,while their inner. end tilt shown, but that the means anfacconstruction toward the overhanging commutator bars herein disclosed comprises the preferred against the tension of the elastic band 12. form of several modes of putting the in- The commutator bars in this instance, are Yention into effect, and the provided with the inclined faces 5. before therefore claimed in any of its forms or mentioned, and the slugs have a wiping or modifications within v the legitimate and sliding enga ement thereon. If the sup- Valid scope of the-ap ended claims. porting disc 1s of flexible or yielding mate- Having thus v described my invention I rial, it may yield laterally under the presclaim: sure of the slugs upon the inclined face 5 1. In a short-k circuiting device for comto permit such slugs a reaterange of slid-y mutators, a circular series of independent ing movement, and-suc elasticity or spring Contact slugs concentrically arranged in of the disc is utilized to insure perfect co-njuxtaposition to the lateral face of the comtact at all times. In this instance the supmutaOl and IIlOVable mdiuyimO ellg'g`- porting disc 20 and the retaining or housment with the commutator bars by centrifing disc 23, are preferably mounted upon or ugal influence, said slugs being bifurcated secured to a collar Aor hub 24, which in turn on their inner ends, a supporting and guide is mounted upon the armature shaft 1. disc the periphery of which is straddled by The construction shown in Fi 8 differs the bifurcated slugs and a contractile band from those previously describe thru the against the tension of which the series of fact that the slugs or centrifugally conslugs is capable of distention under centriftrolled members do not directly engage the ugal influence. Y commutator bars, but in lieu thereof, the l2. In a short ci'rcuiting device for com mutators, a disc mounted in a parallel plane spaced from the lateral face of the commutator, bifurcated contact slugs arranged in a-concentricseries about said disc with theinfurcations straddling the pe ripheryV 'of the disc,l and an elastic band against the tensionof which the slugs are movable into engagement with the commutator bars by centrifugal infiuence.

3. In al short circuiting device for commutators, a circular series of independent contac slugs concentrically arranged in juxtapo tion to the lateral face of the commutator, an elastic band against the tension of which the slu under centrifugal influence, and means for guiding said slugs in a direction inclined to' t-he axis of rotation into contact with the Y commutator bars duringtheir movement under centrifugal influence.

4. In a short circuiting device for commutators, an expansible and contractible series of contactelements controlled by centrifugal influence and means for guidin said' elements diagonally into contact wit the commutator bars while being expanded under centrifugal influence.

5. In a short ci'rcuiting device for combmutators, a 'concave-convex disc located in spaced relation with the lateral face of the commutator, an expansible and contractible series of contact members controlled by centrifugal influence, said lcontact members being guided by said concavo-convex disc during the movement ,under centrifugal. inthe principle involved or sacrificing any of uence in a direction inclined to the axis its advantages. of rotatlon.. y

While in order to comply with the statutes 6.' In a short circmting dence for comthe series of slugs in their assembled relation.j 4Undercentrifugal influence the inor housed within a peripherally flanged or cup disc 26, the marginal flange of which is slotted to form a succession of tongues or yielding fingers 27, overhangingthe peripheral faces of the assembly of slugs. The slugs in their outward movement against the reslstance of the elastic band l2 engage the flexing such fingers outwardly into wiping mutator bar. To insure a clean wiping contact, the extremities of the flexible fingers or contact slugs 26 are preferably bent outsurfaces or contact shoes of greater extent. The slugs are retained within the overhanging fingers or contact ton es,intermediate the supporting disc, and t e' core of the commutator. If a unitary structure is desired, capable of being removedfrom and applied to motors, as a unit,ithe disc may be mounted upon a collar or hub 28 which carries at the inner side of the series of slugs a second disc or ring 29 to retain the slugs or centrifugally controlled mem-bers when the unit is removed from the motor.

From the above description it will be apparent that there is thus provided a device of the character described possessing the particular features of advantage before enumerated as desirable, but which obviously is susceptible of'modification in its form, proportions, detail construction and arrangement of parts Without departing from invention is gs are radially movablek *asA 8. In a short mutators, a circular series of H-shaped conmutators, a concavo-'convex disc located in spaced relation with the lateral face of the commutator, a circularseries of bifurcated contact slugs moiinted about the periphery of the disc with their furcations straddlin the edgc of the disc, said circular series o contacts being expansible under centrifugal influence an guided diagonally into contact with 'the commutator bars by said disc durinlg the expansive movement.

'7. n a' short circuiting device for commutators, a series of contact slugs having notches in their opposite edges, a disc positioned in spaced relation with the lateral ace of the commutator over the periphery of which the notches in, the inner edges o the slugs engage, and an elastic band engaging in the notches in the outer edges of the slugs against the tension of which the series of slugs is movable into engagement withfthe commutator bars against centri ugal inuence. A e

circuiting device for comy' between the furcations inuence,

f withl the tact slugs, gaging between the furcations of one end of the slugs, and an elastic band engagin of the opposite en of the slugs against the tension of which the series of slugs is expansible into contact 80 with the commutator bars under centrifugal iniuence.` 0

9. In a short circurtlng device for commutators, a circular serles of centrlfugally actuated contact slugs` having notches 1n 85.

thelr inner edges, expansible into contact with the commutator barsiunder centrifugal and a supporting disc about the periphery of which t slugs are arranged periphery o ga 'ng within said no hes.

n testimony wherebf, I have hereunto 'set my hand this 22nd lday of November,

A. D. 1921. v

- EVERETT P. LARSH. Witnesses:

G. C. s.

a supporting disc therefor en- 2j5 the dlsc normally enl 

